The subject matter of the invention is the use of 3-amino-5-alkyl-1,2,4-triazoles, hereafter called AAT for short, to prevent corrosion of nonferrous metals in aqueous, particularly industrial water, systems.
Because of their corrosion resistance, nonferrous metals, such as copper, brass, bronze, etc., are preferred materials in the construction of water-conveying plants, for example, steam generating plants, heating systems, cooling water circulating systems and the like. These materials are of particular importance for condenser tubes in steam power plants. Despite their relatively good resistance to corrosion, it is unavoidable, however, that analytically determinable amounts of copper will be given off to the surrounding water in normal use. These copper traces become cemented onto the following cooling water pipes of steel or other base materials, and cause pitting corrosions which are sometimes disastrous. For this reason an additional treatment of the water coming in contact with the nonferrous metal is technically important to reduce this copper transfer. In practice, there are very few inhibitors which are suitable for this purpose. Essentially, these are mercaptobenzthiazole, benzotriazole and tolyltriazole. These compounds are relatively effective as inhibitors of copper corrosion, but they have the great disadvantage that they are chemically relatively difficult to produce and thus can find only limited application for economical reasons. Another disadvantage of the above-mentioned compounds is their very poor solubility at acid pH values, so that a practical manufacture of these products is difficult.